Treatment of cellulose and products obtained therefrom



g UNIT D STAT Patented Jan. 8, 1935 JELLULOSE AND Prion i t U T QFT IN D EREE OM Henry Dreyfus, LondomEngIand i 4 braw ge nD ication-iuly23 193ll, s a-'1 No. -Q f Q JG w i ain August16,'1929 e s, (Cl. 260-101).,

T This invention,isafiQntinuation in part io f gt he inventions of my prior U. S. applications S Nos.

perior results are obtained if the cellulosic ma- ,terials. to be esterified contain more than 8% .of water and still better results are obtained if .the cellulosic materialscontainm, .15, 20 or,30% 1 or more of water.

According to the present invention, therefore, cellulose acetate or other cellulose esters are ob tained by esterificationwith; aliphatic anhydrides of cellulosic materials containing more than 8%, r and preferably more than 10 or 15%, ot-water in presenceof metal halides alone or in admixture {with hydrohalide acidsu v Theactual esterification may beweffected by any of the processesof my said prior spcifica tions,.-namely by treatment with acetjic acid or other; aliphatic acid anhydr'ide in presence of halidesand particularly chlorides iron, tin,

, cobalt, nickel, manganese or coppertogetherwith jhydrohalide acids-starting witha cellulose or a cellulose containing material which contains -35 "hydrochloric acid, hydrobromic acid or hydriodic acre; or in presence of ferric chloride orbromide sole catalyst. Preferably such catalysts are employed in a proportion of morethan2% of y my t ,1

into the cellulose by any suitable method. Preferably the cellulosic materialis impregnatedwith the metal haliderelative to the cellulose, and in the case of using a hydrohalide acid this also is n preferably present in Ia DrODO iB 0f molle a a V i esterification, or prior to effecting the pretreat- 2%. The best results are obtained by effecting "the treatment with, thealiphatieacid anhydride in presence of to %Fof metal halidefwith ii -10 of hydrohalide acid,.though very good" 45 results arealso obtainable with '5" to of ferric t p I pressed out,juntilthecellulosic material retains the required amount. It maythemif desired, be allowed 'to stand before applying the ing"stannic halides. l Furthermore as is described in my U. S. applichloride or bromide used alone orthe correspondcations 8. Nos. 470,229 and 470,231, the esterifi 50 cationmay be carried out in presenceof aferric chloride or bromide catalyst containing agreater quantity of iron than that which corresponds with the chlorideor-bromide present. such excess of iron may, for example, be presentin'the form of ferric oxide or ferric hydroxide, and may "be introduced; either sueh 131m 1 the; acetylating L l mixture or may be formed. therein by partial neutralization-of ferric, chloride or ,-fer ric bromide.

'Againthe proportion of chlorideor bromide rad iclegtoiron may varyduringtheaetual esterifi- 5 cation. For example theesterification may be begun in presence of ferric chloride and hydrochloric acid and during the, esterification the acid wholly orin part neutralized, and if desired the halide radicle itself may also bepartlyneu- :10 tralized, the neutralization being effected in one or more stages. Similarlythe esterification may.

be begun in presence of ferric chloride, and a partial neutralization effected at {a later). stagev or ,on the contrary hydrochloric acidadded.

.15 .As' with the 1 processes of my earlier applications, the best results are obtained by pretreating the"cellulosic materials before esterification with organic acids, and particularly lower fatty acids,

such as acetic acid or'formic acid and/or with the, metal halides or hydrohalide acid to be used in the subsequent esterificationlj'j Pretreatments with formic acid, acetic or other lower aliphatic acidsmay be, applied in the liquid state, or may jbe alone ormixed with inertgases. The pre- L treatment with organic acids maybe carried out with acids of any desiredconcentration, for example 50, 80, 85 or 100" per cent acetic. or formic acid, and in large or small quantities.

The important advance represented, by the present invention consists inf obtaining superior cellulose esters by. carryingout the esterification in presence of metalihalides, with or without more than 8% of waterand preferablymore than 10 or 15%. The watermay be introduced the. water sometime prior toefiecting the actual Cotton, or other celments referred to above.

lulosesjor other cellulosic materials, may, for

tion or the pretreatment processes.

Alternatively the cellulosic material may be allowed to soakor steep in an. excess of water for sometime-prior tome hydroextraction or pressing out." Chemical 'woodfpulps are preferably subje'cte'd to an alkalineipurifying treatment 'tate, comprising acetylating wmore than 10% sisting of iron, tin,

copper. p

13. Process for the production ofcellulose acetate, comprising acetylating cellulose containing excess water over the hygroscopic content by means of acetic anhydride in the presence of hydrochloric acid and a chloride of a metal selected from the group consisting of iron, tin, cobalt, nickel, manganese and copper.

i 14. Process for the production of cellulose acecellulose containing of water by meansof acetic anhydride in the presence of a chloride of a metal selected from the group consisting of iron, tin,

cobalt, nickel, manganese andcopper. Y 15. Process for the production of cellulose acetate, comprising treating with a lower aliphatic acid cellulose containing excess water over its hygroscopic content, and thereafter acetylating the same with acetic anhydride in the presence of a chloride of a metal selected from the group consisting of iron, tin, cobalt, nickel, manganese and copper.

16. Process for the production of cellulose acetate, comprising treating with a'lower aliphatic acid cellulose containing excess water over its hygroscopic content, and thereafter acetylating the same with acetic anhydride in the presence of hydrochloric acid and a chloride of a metal selected from the group consisting of iron, tin, cobalt, nickel, manganese and copper.

HENRY DREYFUS. 

